Got Homework?
Connect with other students for help. It's a free community.
Here's the question you clicked on:
 0 viewing
Idealist
Group Title
If we intercept an electron having total energy 1533 MeV that came from Vega, which is 26 ly from us, how far in lightyears was the trip in the rest frame of the electron?
 one year ago
 one year ago
Idealist Group Title
If we intercept an electron having total energy 1533 MeV that came from Vega, which is 26 ly from us, how far in lightyears was the trip in the rest frame of the electron?
 one year ago
 one year ago

This Question is Closed

Carl_Pham Group TitleBest ResponseYou've already chosen the best response.0
You need to work backward from the relativistic momentumenergy formula to find the velocity of the electron in our reference frame, then use that with the LorentzFitzgerald contraction to find the ratio between the distance in the electron's frame and in ours.
 one year ago

Carl_Pham Group TitleBest ResponseYou've already chosen the best response.0
Here's the first part: http://hyperphysics.phyastr.gsu.edu/hbase/relativ/releng.html
 one year ago

gleem Group TitleBest ResponseYou've already chosen the best response.1
From the special theory of relativity \[t' =t/\sqrt{1v ^{2}/c ^{2}}\]where t is the time in the electron's reference frame and t' is the time in our reference frame and v is the velocity we observe . Also from the special theory we have\[E=mc ^{2}=m _{0}c ^{2}/\sqrt{1v ^{2}/c ^{2}}\]where \[m _{0}\]is the rest mass of the object . The rest mass of an electron is .511MeV Solve for t in terms of v,E and mo.
 one year ago

Idealist Group TitleBest ResponseYou've already chosen the best response.0
mc^2=8.187*10^14 J (8.187*10^14)/1533=5.34*10^17 What do I do after that?
 one year ago

gleem Group TitleBest ResponseYou've already chosen the best response.1
Because energy can be expressed in electron volts and mass can be expressed as energy (E=m0*c^2) you do not have to change to joules and kgms in this problem. You can if you want but you must work with the rest mass in kgm the velocity of light in m/sec and energy in joules. what do we need to do first. We want the time in the moving reference frame of the electron,t. We have the equation that relates that time to the observer time on earth, t'. we know c. So we must find the velocity of the electron with an total energy of 1533 MeV. Actually we only need to find (v/c)^2. since that quantity appears in the two equations we are using. Since we have the total energy of the electron (i.e. rest mass energy +KE) E=1533MeV we can find its velocity. with the equation\[E=mc ^{2}=m _{0}c ^{2}/\sqrt{1(v/c)^{2}}\] E=mc^2 =.1533MeV solve for v/c and substitute that into the time equation to find t. remember m0c^2=0.511Mev and t'=27 years.
 one year ago

Idealist Group TitleBest ResponseYou've already chosen the best response.0
I get it now. Thanks.
 one year ago
See more questions >>>
Your question is ready. Sign up for free to start getting answers.
spraguer
(Moderator)
5
→ View Detailed Profile
is replying to Can someone tell me what button the professor is hitting...
23
 Teamwork 19 Teammate
 Problem Solving 19 Hero
 Engagement 19 Mad Hatter
 You have blocked this person.
 ✔ You're a fan Checking fan status...
Thanks for being so helpful in mathematics. If you are getting quality help, make sure you spread the word about OpenStudy.